Tool Authoring
Use when creating, modifying, reviewing, or debugging Theseus Tool primitives or concrete tools in packages/theseus-core/src/tool and packages/theseus-tools.
Install
$ agentstack add skill-theseus-run-theseus-tool-authoring ✓ scanned · ✓ verified, works with Claude Code, Cursor, and more.
Security review
✓ PassedNo issues found. Passed automated security review. · v0.1.0 How review works →
- ✓ Prompt-injection patterns
- ✓ Secret / credential exfiltration
- ✓ Dangerous shell & filesystem operations
- ✓ Untrusted network calls
- ✓ Known-malicious package signatures
What it can access
- ✓ Network access No
- ✓ Filesystem access No
- ✓ Shell / process execution No
- ✓ Environment & secrets No
- ✓ Dynamic code execution No
From automated source analysis of v0.1.0. “Used” means the capability is present in the source — more access means more to trust, not that it’s unsafe.
Verified badge
Passed review? Show it. Paste this badge into your README, it links to the public security report.
Links to your public security report.[](https://agentstack.voostack.com/security/report/skill-theseus-run-theseus-tool-authoring) Reliability & compatibility
Declared compatibility
Compatibility is declared by the source manifest. End-to-end runtime verification is coming, see below.
We're building live execution health for every listing: tool-call success rate, median latency, uptime, and last-checked timestamps, measured, not self-reported. It isn't live yet, so we don't show numbers we can't stand behind.
How agent discovery & health will work →About
Tool Authoring
Use this skill for Tool primitive work and concrete tools.
Read First
packages/theseus-core/src/Tool.tspackages/theseus-core/src/tool/index.tspackages/theseus-core/src/tool/run.ts- For concrete tools: the relevant file in
packages/theseus-tools/src/
Contract
A tool is typed world access for the model. It declares input, output, known failure, execution, presentation, and interaction policy.
Preserve this pipeline:
- Decode raw model args with
tool.input. - Run
tool.execute, applyingtool.retryif present. - Validate success output with
tool.output. - Validate known failure with
tool.failure. - Present success or known failure as
Presentation. - Convert defects into
ToolDefect.
Known failures are tool-result content for the model, not runtime exceptions. Runtime errors are decode, output-shape, failure-shape, and defect errors.
Authoring Rules
- Use
Tool.defineTool; do not create ad hoc tool objects unless testing a boundary directly. - Use Effect Schema for
input,output, andfailure. - Use
Tool.Defaults.NoFailureonly when the tool has no declared domain failure. - Keep tool names stable and LLM-callable.
- Keep descriptions operational: what the tool does, not implementation trivia.
- Set
policy.interactionintentionally. Do not default write-like behavior to observe/read semantics. - If a tool touches the filesystem, shell, network, or process state, model that risk in policy and failure shape.
- Prefer small concrete tools over a generic "do anything" tool.
Verification
- Run the package-local test when changing
packages/theseus-tools:bun test src/from that package or rootbun run testwhen impact crosses packages. - Run root
bun run typecheckwhen signatures, schemas, exports, or Effect environments change.
Source & license
This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.
- Author: theseus-run
- Source: theseus-run/theseus
- License: MIT
- Homepage: https://www.theseus.run
Install and usage instructions live in the source repository linked above.
Reviews
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Versions
- v0.1.0 Imported from the upstream source.